High gain frequency multipliers



Sept. l1, 1956 B. WISE HIGH GAIN FREQUENCY MULTIPLIERS Filed March 3l, 1954 BERNHBD WISE Lrmwn Uu IN V EN TOR.

TTo RNE/ Sept. 11, 1956 B. WISE 2,762,918

HIGH GAIN FREQUENCY MULTIPLIERS Filed March 3l, 1954 5 Sheets-Sheet 2 1 VENTOR. i l, BERNHRD 15E BM H. @um

ATTa/wA/Ey Sept. 11, 1956 B. WISE:

HIGH GAIN FREQUENCY MULTIPLIERS Filed March 31, 1954 [fd/wiwi.

5 Sheets-Sheet 3N,

United States Patent O HIGH GAIN FREQUENCY MULTIPLIERS Bernard Wise, Philadelphia, Pa., assignor to Radio Corporation of America, a corporation of Delaware Application March 31, 1954, Serial No. 420,036

'l5 Claims. (Cl. 250-36) The invention relates to frequency multipliers, and it particularly pertains to means f oripgreasrigggeuppnwer rgainlof suchmuliipliers.

Frequency multiplying arrangements are known in the art. Perhaps the most common form is that in which the non-linear relationship which exists between the grid voltage and anode current, or the non-linear relationship between the grid voltage and the grid current, of a vacuum tube is used to produce output currents which include components of the desired frequency. These components are selected by some suitable means, such as a sharply tuned filter. A class C amplifier may be used as a frequency multiplier by tuning the output circuit to a multiple of the frequency of the driving source. As the output frequency is increased, the output power will decrease at a rate greater than the rate of frequency increase. Also, the grid driving losses tend to increase with the degree of multiplication because an increasingly higher bias is required to decrease the width of the plate current pulse as the ratio of output to input frequency is increased. The only known alternative is to reduce the bias, letting the current flow through a larger portion of the tube operating cycle, and operate the tube at lower anode efficiency. Usually, this requires a reduction in amplifier output to prevent excessive anode dissipation. The dis-y advantage is so great that it is usually considered more economical to use two known frequency doubling circuits rather than a single frequency quadrupling circuit, and so on.

An object of the invention is to irnprgvewggpowgr gain ofmfmrequengywmultiplwiwerr rligements. '"thefbject is to Avdecrease ihe losses which occur within the vacuum tube and the associated circuitry of the frequency multiplier and which limit the output power, so that greater output power is realized than is now obtainable with arrangements of the knownart.

A further object of the invention is to provide an improved frequency multiplier circuit structural arrangement.

The objects of the invention are obtained in a frequency multiplying circuit arrangement including an electron discharge device having at least electron emissive, electron control, and electron collectingV electrodes determining input and output terminals, an input circuit coupled to the input terminals comprising the electron emissive and electron control electrodes and to which awave of given input frequency is applied, an output circuit coupled to the output terminals comprising the electron collecting electrode and one other electrode and fromV 2,762,918 Patented Sept. 11, 1956 arranged to present parallel resonance at a frequency higher than the given input frequency in order to eiect a high impedance across the input circuit as a whole at a frequency greater than the input frequency and equal or close to the output frequency, as well as operating in conjunction with the other components of the input circuit to establish parallel resonance and the attendant high impedance across the input circuit at the given input frequency. In such an arrangement the high impedance l"at the given frequency serves exactly as in the prior art quencybwhichisnot pro ,N v. tsgtoaether-wth the Ycoupling...bef .t input c, its inherently PrQYdSdbYfth interelectrode capacitancesmand the ,electron`V flow between the electrodes,v Yprovides a path for energy flow in support of the generation of the harmonic wave at the desired output frequency. According to the invention, in order to obtain regeneration rather than degeneration, the resulting circuit reactance across the entir input circuit is made capacitive fgnagrauraaiigrid yeulplerend. inductive for h a ground d athode multiplier at the output frequency, while theresonance is established atmtlie input frequency. 'Y

The above-mentioned subcircuitry might be arranged so that the input circuit is parallel resonant to provide maximum impedance at the output frequency, except that oscillation at the output frequency will then be established. l a structure involving a grounded-grid ampliiier, it has been found that the desired results are obtained when the input circuit is made parallel resonant at a frequency near the output frequency but lying between the input frequency and the, output frequency. lnmprag; tice, Ythe input Circuit Oia.greundedridtage -.-ade paialllmsh thveillpllt, frequency `and..alsrratlat fregipnjflying.. ctn/een.4%.` and.. ,lZ/JQW than the tput frequency. For the grounded-cathode arrange- "meit""the sub-circuit is made resonant within a similar range altere. thenetpgtlteauency.

The circuit arrangement according to the invention may be obtained by the useV of electron discharge tubes and the like of substantially all types of construction and resonantcircuitry comprising reactance elements of the lumped parameter type, trapsmissio liiief'elements,

or cavity resonatgllglglls. In a grounded-grid cavity A' r'estor'arrangement the desired effect is obtained by sub-circuitry comprising variations of the structure as determined for a given mode to propagate another mode, effecting a series inductance element between the electron emissive electrode and the effective impedance element of the cavity resonator.

In order that the invention may be clearly understood and readily put to practical use, descriptions of several embodiments, given by way of example only, appear below with reference to the accompanying drawings in which:

Fig. l is a schematic diagram of aprior art cathode frequency multiplying circuitarraiig,'A

the invention approximately equivalent to that illustrated in Fig. 4;

Fig. 10 is a schematic diagram of the structure illustrated in Figs. 6-9; and

Fig. 11 is an approximate equivalent circuit diagram showing the feedback path of the arrangement illustrated in Fig. 4.

Referring to Fig. 1, there is shown the fundamental* circuitry of a frequency multiplier known to the prior art. An input resonant circuit 16 comprising the parallel connected inductance element 17 and capacitance element 18 provides a highmimpedancgfor an input wave of given frequency and is connected between the input electrodes 21 and 22 of a vacuum tube 20 or other electron discharge device comprising an electron emissive or cathode elec-g trode 21, a control grid electroden2'2, and an electron collecting or anode electrode 23. An output circuit `26 f comprising the parallel connected capacitance element 27 and inductive element 28 is connected between the anode 23 and the cathode 21. The connections shown and described are made with respect to alternating current, it being understood that the necessary power supply and other direct current connections are not shown in the iigure. The/output circwu it -26 ris tunerdhto afrequency equal to an integralultiplef the given frequency to whicliwtlucifcuit 16 is tuned. In practice, it is necessary in most cases to restrict the tuning of the output circuit 26 to a frequency which is two or three times the input or given frequency, although in'someiis'taicesi'an output frequency four or more times the input frequency has been developed. In the past, it has been considered that the use of two frequency multipliers of the type shown in Fig. l coupled in cascade, in order to produce frequency quadruplication or quintuplication, is desirable, because the magnitude of output from the prior art frequency multipliers is so limited.

The arrangement shown in Fig. 2 is known as the grounded-grid circuit because the input circuit 16 is connected between the cathode 21 and a point of iixed R. F. reference potential, which is usually ground, while 4 the output circuit 26 is connected between the anode 23 and the grid 22, which is connected for alternating current to the reference potential point or ground. The grounded-grid circuit is very stable in operation, although it requires a bit more driving power; otherwise, the same disadvantages and limitations apply to the grounded-grid circuit of Fig. 2 as were described in connection with the grounded cathode multiplier circuit shown in Fig. l. In general, the principal objection to the frequency multiplying arrangementsslwiithese gures is that the maximum power gain obtai ble with these circuit arrangemii "s'itlirmlwfespeci a7; the ultra higlfrequenciesl..." 'www A'example of a circuit arrangement according to the invention, which will provide higher power gain, is shown in Fig. 3. In this arrangement, the tube 20 and the output circuit 26 are essentially as described above in connection with the prior art circuit arrangements. An input Ciit 39.iylasiesuh-similiar/...32 'Comprising an inductive element Q'riirarrdgaV capkac iveeleriient 34having valustwiclfthe sub-circuitry itself is p rallel resonant to a frequency slightly ,higher than 'Vfityfrequ'cy butwwhikcht'ogethe"with'a furthiuiluc ve element 36 ad a further capacitive element 37 having values at which the input circuit as avyvhqole is parallel resgnarithat the input frequency, presentahigh impedance arcross the inpt'circuit`30ias awhole at the output frequency, as well. The cathode 21 is effectively connected to ground by means of a capacitor 41 which offers a low impedance to energy at both the input and output frequencies. Direct operating potentials are applied to the circuit by way of a radio-frequency choke 43 connected to the anode 23 and a cathode bias resistor 45. A'blocking capacitor 47 is interposed between the anode 23'y and the output circuit 26 to prevent the llow of direct current in the latter circuit. The circuit as shown is the well-known shunt fed, self-biased circuit; however, xed biasing can be used if desired, according to the known art. The input wave of fundamental frequency f1 is induced in the input circuit 30 by means ofthe link coil 51 connected to the terminals 53 and 54. The output wave of frequency fu is obtained from the output circuit 26 by means of a similar inductively coupled link 56 connected to output terminals 58 and 59. Obviously, other known methods of introducing the fundamental Wave energy into the input circuit 30, and derivingpthe output wave from the output circuit 26, can be used.

The application of the input circuit according to the invention to a grounded-grid circuit,`is shown lin Fig. 4. The output circuifsmiriic-t'db-tvxeen the" anode 23 of the tube and a point of gvixed referencepotential, preferably ground, by means of a bypass capacitor 61, in the series-fed arrangement as shown.) The capacitor 61 would be obviated if v'the shunt fed'circuit as shown in Fig. 3 were used. The input circuit 30 is connected between the cathode 21 and the'point of fixed reference potential. The grid 22 of tube 20 is connected to the reference potential point or ground `by means of a grounding capacitor 63 and biased to the proper extent by means of a shunt bias applied by way of ther` grid resistor 675K. The grid 22 may be grounded directly if self-biased, for example in the manner shownin the circuit of Fig. 3. Energy at the input frequency is'applied to the input circuit by way of a coupling Vca'pacitorn67"which is tapped onto the further inductance element V36 and connected to the input terminal 68, the other input terminal 69 being connected to the reference potential point or ground. The output wave of frequency fn is obtained from the anode 23 by way of the coupling capacitor 71 leading to a live output terminal 73. The other output terminal 74 is connected to the reference potential, shown here as ground. In the circuit arrangements of Fig. 3 and Fig. 4 a certain amount of energy is coupled from the @man ein@ 26 tu eftl" afibthisiicniipliiig is due to the inter-elec- 'tre' capacities and part of it is` due torvtheinherent coupling by the fjgvuvpgfelegtrpns, hliwcathode 21" to the anguria Even the grounded-grid circuit, which is designed to isolate the input and output circuits as much as possible, exhibits this inherent coupling. By arrang- ,gagnait-t0 in thisiristant@ by Hit-@31.8.0

they outpultpower. v The overall input circuit f course, yalso parallelfr'eson'ant at exactly theinput frequency f1. In Fig. 5 there is shown a graphical representation of the impedance across the entire input circuit with respect to frequency of the circuit of Fig. 4. At the inputmfrequency fr tvhe parallel resonance of uthe c'i-rc-uit i" Y r 'Hlveryigh impedance, infinite impedance iffth-e idealc'a's'e',"and due to the two-pole network shown, PIII'isOnanCe is again obtained at a higher frequency f1. The frequency fi cannot be equal to the output frequency because detrimental oscillations would then occur at the Output frequency. Thejnnutrirnitao.initier@- fore, made parallel resonant to a requency fiwwhichmis snvvggdiffGIQ-.HItH'"utputwffeuquency fn. In practice, the intermediate frequency fi for a groundedgrid amplifier should lie between 4% and 12% lower than the output frequency and about the same amount higher for the grounded-cathode circuit. The impedance across the circuit 30 at the frequency fn is still very high, as is shown in Fig. 5, and it -is' capacitive in nature. From this curve, it is seen that the input circuit 30 is a two-pole network parallel resonant at the input and intermediate frequencies. Another factor to be considered is the effect of phase shift, which is inherent in all tuned circu`its of this type. The spread between the intermediate and out- 75 put frequencies can be adjusted not only to provide high f the i, itive impedance at the output frequency and capacitive reactance at the output frequency in circuit 30, but also to provide a phase shift which is more favorable to the desired condition of operation.

Transmission line elements and cavity resonator circuitry niy'bwed'siib's'titutdmfor the l\\`1`mped"*'reactance"type of circuitry shown inthe diagrams. Figs. 6-9 show a frequencywdgubller using cavity resonator circuitry along theliiiestatight by the applicants copending U. S. patent application Ser. No. 322,909, filed November 28, 1952. According to the teachings in the copending patent application, and in accordance with the present invention, frequency multiplication may be obtained in the arrangement shown in Figs. 6-9 comprising an electron discharge device or vacuum tube 111 having an anode terminal 113, a control grid terminal 115 and a cathode terminal 117. The cavity resonator structure includes tuned input and output cavity resonators for the vacuum tube discharge device 111. As shown, both the input and output cavifties are rectangular in shape with the vacuum discharge device 111 extending through registered apertures in the cavity walls centrally of each cavity. These two cavities are preferably defined by three flat walls. The input cavity 121 is contained between a first or cathode wall 123 and an intermediate or grid wall 125. The output cavity 127 is formed between the intermediate or grid wall 125 and a third or anode wall 129. The input cavity 121 is closed by two iixed parallel Walls and two adjustable shorting bars 131. Similar sets of fixed walls and adjustable shorting bars 133 close the output cavity 127.

An anode contacting ring 135 is maintained in insulated relationship to the third or anode wall 129 by dielectric spacers 136 and 137, but is mechanically secured to the anode wall by a hold-down ring 138. The insulating spacers 136 and 137 perform the function of direct current isolation for the high anode voltage and further form a bypass circuit for radio frequencies between the anode contacting ring 135 and the anode wall 129.

A-grid terminal contacting ring 139 is carried by a rectangular metallic block 14T-which is positioned in the output cavity. The rectangular metallic block 141 has a cylindrical aperture therein in registry with the apertures in the walls 125, 129 to receive the vacuum tube 111 and is secured to the intermediate or grid wall 125 by a pair of oppositely disposed clamps 143, shown in Figs. 7 and 8. The rectangular block 141 is maintained in insulated relationship to the intermediate wall 125 and the clamps 143 by dielectric spacers 145, 147. The insulating dielectric spacers 145, 147 provide for direct current isolation for the grid of the vacuum tube 111 and form a radio frequency bypass circuit between the grid terminal contacting ring 139 and the intermediate grid wall 125.

The teachings of the aforementioned copending application are modified in the structure according to this invention, in order to providethe additional resonance at the intermediate frequency. Thi'smismaccor'iipli'shed by varying the length of the cathode coaxial stub to alter the conditions in the input' cavity 121. A longer stub is shown in Figs. 6 and 7. Th'leiigth of this coaxial stub is more or less inverselyL proportional to the frequency. A longer stub is required for the lower input frequencies and a shorter stub is required for the higher input frequencies to which the cavity is tunable. The shortened stub is constructed in essentially the same" manner as taught in the copending application, except that it is cut down to the desired length for operation in a different manner according to this invention.

For a vacuum tube discharge device 111 having a coaxial cathode and heater terminal arrangement, as shown in Figs. 6 and 7, a cathode terminal contacting ring 151 carried within a cylindrical member 153. For shortened stub construction, the cathode terminal member 153 has an integral flange thereon for mechanically securing the block 153 and cathode terminal contacting ring 151 to the resonator structure as shown in the copending application, the difference being in the stub length. Dielectric spacers are again used to isolate the cathode for direct current potentials but to form a radio frequency bypass circuit between the cathode terminal contacting ring 151 and the rst or cathode Wall 123.

When the stub is lengthened an additional tubular member 205 is used to extend the cylindrical member 153 and a further tubular member 207 and annular ange or disc member 209 are used to return the outer end of the coaxial stub to the connection point for the lead as shown in both Figs. 6 and 7.

With coaxial type heater-cathode terminals, as shown, the cathode terminal 117 is internally connected within the vacuum tube to one end of the heater lament, and the other end of the heater filament is brought out to a pin contained coaxially with the cylindrical cathode terminal 117. A jack terminal 163 mechanically and electrically engages the heater terminal to supply the heater current to the discharge device 111. A cathode and heater lead 165 (Fig. 7) is electrically connected to the cathode member 153 and a heater lead 167 (Fig. 6) is electrically connected to the heater jack terminal 163.

A pair of metallic blocks 171, 172 are positioned in the inputucayity 121 in close'proximityutowthe terminals of the vacul-b`efIIIfThese metallic blocks 171, 172 are connected Ptthev `first -r` `iatl`1ode` wall 123 and effectiveliI forni a very lowriipedance line section betweeilivmajnugrnltnhe;ternnalsrand" the rremainder of the input cavity 121. Thiserlw'ijmpedance line section formed between the'blocks 1715117.2"nd'the adjacent intermediate or grid wall 125 acts to increase the electrical length betweenwginglegtrgdes ofthe'vagepllmtubeflll fha-invention .thegspes between the-*blacksiiij and 172 and the grid Wallljz nljtlrlllcjedto approximately one.'- fourth the dimensions taughtfinthe copending applica'- tion, to aid in producing the desired double resonance condition necessary'for operation according to this in- Ventron. j

Referring now to Fig. 7, which is a cross-section of the same device shown in Fig. 6, taken along the center line thereof in a direction transverse to the view of Fig. 6, there is shown means for coupling radio frequency energy at a frequency f1 into the input cavity 121 and means for deriving radio frequency 'energy from the output cavity 127 at a frequency fn.

The radio frequency input at the frequency fr is applied through a short section `of coaxial line having a cylindrical outer conductor 173 connected to the first or cathode wall 123 and an inner conductor 174 which extends through an aperture in the first or cathode wall 123 and terminates in a coupling disc 175 (see Fig. 9) in closely spaced capacitive relation to the intermediate or grid wall 125. This input coupling arrangement electrostatically couples the radio frequency energy between the flirsst or cathode wall 123 and the intermediate or grid wall The arrangement for extracting energy at the frequency fn from the output cavity -127 is similar to the input coupling just described, and includes a coaxial output line 181, 183 having its outer conductor 181 electrically and mechanically connected tothe anode wall 129 and its inner conductor 183 terminated in a coupling disc 185 (see Fig. 8).

In Fig. 8, a top plan view of the device of Fig. l1 shows in detail the output cavity 127 withgthe third or anode wall 129 removed, as indicated by the line 8-8 of Fig. 6. In this figure,` the relative positions of the output coupling arrangement, including the coupling disc 185 and the inner conductor 183 of the output line relative to the rectangular metallic block 141, are readily apparent.

Referring now to Fig. 9, there is shown a plan view of the input cavity 121, as indicated by the line 9--9 of Fig. 6. The relative positions of the input coupling arrangement in plan are shown, including the coupling disc 175 and the inner conductor 174 of the output transmission line. i Y- fw A schematic diagram of the structure illustrated in Figs. 6-9 is shown in Fig. 10. When the input cavity 121 and output cavity 127 are excited with radio frequency energy, transverse electric waves are set up in the longitudinal direction, that is, between the shorting blocks 131 in the input cavity 121 and between the shorting blocks 133 in the output cavity 127. Thesewlongitudinal waves are in the plane of the drawing i Fig. 6 and perpendicular to the plane of the section iii Fig. 7. L/The length of the input cavity 1,21is such that from the vacuum tube elec- Vtrodes inside the vacuum tube 111 to the shorting blocks 131 is one-quarter wavelength for operation over a large portion of the frequency band desired.

The input cavity 121 is also r'e'sonant to the interresultsftlwsb-ciitdil'thespreviisly 'scribed embodiments ofFigs. 3 and 4 arepneffected by the tuning of the cathode blocks M171,M "1l/ 2 and thelgth of the cathode stub coaxial transmission line. The equivalent operational circuit of the grounded-grid dubler arrangement is shown in Fig. 11. I tcanY Vbemseenjhat energy at the output frequency is fed back into the input circuit impedance 211 by way of the anode-tQ-cathode capacitance represented by the capacitor `213. The exact phase of this feedback energy is dependent on the character of the impedance between the grid and cathode at the output frequency. When this latter impedance is capacitive in nature at the output frequency, regenerative feedback is obtained. This is accomplished in the cavity resonator circuit by the series inductance connected between the cathode terminal 117 and the cathode wall 123 in the form of the coaxial stub. 'Illusmllthreequarter wave mode is always resonant to a frequency lower'than'`tleiitfpt"flij` meq'e'ncy' intermediate the input and output f qincies. Care is taken in tuning to see that the magnitude of the feedback never rises to a level that can cause instability.

Starting at the tube electrodes inside the vacuum tube 111, the metallic blocks 171, 172 are outside the rst quarter wave point of the standing wave of voltage for the resonant frequency, that is', more than one-quarter, but less than one-half, wavelength at the operating frequency from the vacuum tube electrodes.

In the input cavity 121, the input coupling arrangement consisting of the coaxial linesection 173, 174 and the disc 175 couples energy directly into the cavity. Theoretically, this coupling point exists in the cavity at a point at which the resonator is effectively beyond cutoff. However, practically, the input cavity 121 is designed so that the attenuation is not sutiicient to prevent setting up the TElo mode in the longitudinal direction and to permit its being propagated in the transverse direction. Therefore, the signal will be developed across the vacuum tube electrodes.

In the output cavity 127, the output coupling arrangement 181, 183, 185 extracts energy from the longitudinal eld. This longitudinal field is greatest in close proximity to the rectangular metallic block 141, that is, nearest the vacuum tube terminals. The greatest output coupling could be had by positioning the output coupling arrangement 181, 183, 185 immediately over the rectangular metallic block 141. However, suicient coupling is achieved at practically all frequencies by the arrangement of Fig. 7. Other workable alternative systems for deriving output waves from the output cavity 127 are described in the above mentioned copending application.

When operating the cavity resonator circuit described as a frequency doubler in conjunction with a concentrically constructed vacuum tube electron discharge device 111, the input cavity 121 between the grid terminal contacting ring 139 and the cathode terminal contacting ring 151 is tuned to resonance at the desired input frequency. For ultra high frequency television transmission, this input frequency will be between 235 and 445 megacycles. The short-circuiting bars 131 are adjusted so that the first quarter-wave point away from the tube electrodes occurs at the short-circuiting bars 131. Stated in another way, the input stage in doubler operation is operated in the TEio mode.

The output stage in doubler operation, that is, the cavity 127 between the control grid contacting ring 139 and the anode contacting ring 135, is tuned to the desired output frequency by positioning the shorting bars 133 at the first quarter-wave point from the tube electrodes. For ultra high frequency television, this frequency will be between 470 and 890 megacycles. Due to the physical and electrical arrangement of the cavity 121, the input circuit in doubler operation Will not support a three-quarter wave mode, that is a TEso mode, as an integral multiple of the input frequency. This is due to the fact that, with the dimensions of the cavity and the blocks 171, 172 in the input cavity, the length of the input cavity is not the proper value to support the threequarter wave mode of operation for any multiple of the input frequency.

One embodiment of the invention successfully operated in practice was designed with the input cavity 121 operable over a range of frequencies from 235 to 445 megacycles and the output cavity 127 operable over a range of frequencies from 470 to 890 megacycles, with the following dimensions. The electron discharge device 111 was a type 616-1 ultra high frequency power triode. The first or cathode wall 123, the intermediate or grid wall 125 and the third or anode wall 129 were made of 3/32 inch silver-plated brass. The spacing between the first or cathode wall 123 and the intermediate or grid Wall 125 was 1%@ inch. The spacing between the intermediate wall 125 and the third or anode wall 129 was 1%6 inches. The shorting bars 131 in the input cavity 121 were 1% inch high, 5A@ inch thick and 71/2 inches long, and carried in the channels therein springs.191 of a closely wound helical configuration made of silverplated Phosphor bronze wire 0.015 inch in diameter, the diameter of the helix being 1A inch. The maximum distance between the shorting bars 131 was 9% inches, and the minimum distance to which they were adjustable was approximately 2% inches. The blocks 171 and 172 were also of silver-plated brass and had a length in the longitudinal direction of the cavity of 1/2 inch, were 3 inches long in the transverse dimension and were roughly 1%6 inch high, that is, roughly equal to nominal cavity wall spacing. The blocks 171, 172 actually did not touch the intermediate wall 125, but were insulated therefrom by a teflon spacing member 0.0100 of an inch thick. This is one-fourth the distance used in the amplifier structure described in the copending application.

The shorting bars 133 in the output cavity 127 had the same thickness and length as the shorting bars 131 in the input cavity, but had a height of 1 inch. The contacting springs 191 in the shorting bars 133 were identical to those used in the input cavity 121. The rectangular metallic block 141 in the output cavity 127 was of silverplated brass and had a length of 3 inches in the longitudinal direction of the cavity, was 21A inches Wide, 15/16 inch thick, and included a cylindrical bore 11/2 inches in diameter to receive the type 6161 vacuum tube. The

- spacing between the rectangular block 141 and the anode wall 129 was lz inch. The anode contacting ring 135 and the grid terminal contacting ring 139 were helical springs identical to those used in the shorting blocks 131 and 133; while the cathode terminal contacting ring 151 was a helix made of the same wire, but having a /g inch diameter, rather than a 1A; inch diameter like the others. The input and output coupling arrangements included short sections of coaxial lines 173, 174 and 181,

183 in which the inner conductors 174, 183 were of silverplated brass rod %2 inch in diameter, and the inside dimension of the outer conductors 173, 181 was 3A inch. The discs 175, 185 were each 1% inch in diameter and 3/32 inch thick. With this arrangement, power gains of 2-3 were obtained over the range of frequencies to which the circuit could be tuned as a doubler.

The invention claimed is:

1. A frequency multiplying circuit arrangement comprising an electron discharge device having at least three electrodes determining input and output terminals, ian input circuit coupled to the input terminals to apply a wave of given frequency to said electron discharge device, said input circuit beingV constructed 4Vand arranged to be parallelwresonant at said Vgiven frequency, an additional impedance coupled to said input Vcircuit to causeA such circuit to present a high impedance at amfrequency substantially greater than`1 the frequency of"said"g'iv'frequency wave, and an output circuit coupled to the output terminals to derive an output wave having a frequency which is a frisltirlecfaid .siren frequency- 2. A frequency multiplying circuit arrangement as deined in claim 1, wherein said additional impedance is connected gto cause said input circuit to be parallel resonant at a frequency near but ot equalhtor'the frequency of said output wave) 3. A frequency multiplying circuit arrangement as defined in claim l and wherein 'said input presents a relatively high value of capacitive impedance at a frequency substantially equal to the frequency of said output wave.

4. A frequency multiplying arrangement as defined in claim 1, wherein said high impedance presented is inductive in nature.

5. A frequency multiplying circuit arrangement as dened in claim l, wherein said input and output circuits and said additional impedance comprise lumpedreactance elements. W

6. A frequency multiplying circuit arrangement including an electron discharge device having cathode, control and agpde electrodes each substantially confined to an j individual plane in parallel relatignshiptothe other planes, I wall members lying isidplanes, and further wall memybers forming close'cdzyglumes in conjunction with the first l I,said wall mm'/fs'jtlewall neiiibrs associated with said control anode electrodes in conjunction with the interelectrode space forming alcaayitywresonator circuit tunedA f hviemwning wallto a predetermined frequency, and4 members associated witlsaid cathode and control electrodes in conjunction with the inter-electrode space forming another cavity resonator `'circuit tuned to a frequencywhich is a sub-mumlntiglggfsaid predetermined frequencyand present'i'gsubstantially high impedance" to energy' at said predetermined frequency.

7. A frequency multiplying circuit arrangement as defined in claim 6, wherein said other cavity resonatorcircuit is parallel resonant at a frequency lying between four and twelve percenntbpelnowwsaid predetermined frequency.

8. A frequency multiplying circuit arrangement as dened in claim 6, wherein said other cavity resonator circuit incorporates means torloadthesame to provide rcsonance at theLtmeeu-quarterrvalvemode.

9. A frequency multiplying'cicuit arrangement as deiined in claim 6, wherein a length of coaxial transmission line is connected between theglillgqleftrode and one wall meinbermof said othcrjcayity resonator circuit.

V'1021A frequency multiplying circuit arrangement as defined in claim 9, wherein said coaxial transmission line length is of a value at which inductive reactance is presented, at said predetermined frequency, between said cathode and said one wall'member of said other cavity resonator circuit. "W"

11. A frequency multiplying circuit arrangement as deiined in claim 9, wherein said said coaxial transmission line length is of a value at which capacitive reactance is established across the cathode and control electrodes at said predetermined frequency.

l2. A frequency multiplying circuit arrangement comprising an electron discharge device having at least three electrodes determining input and output terminals, an input circuit coupled to the input terminals to apply a wave of given frequency to said electron discharge device, said input circuit being constructed and arranged to be parallel resonant at said given frequency and to present a high impedance at such frequency, an output circuit coupled to the output terminals to derive an output wave having a frequency which is a multiple of said given frequency, and an additional impedance coupled to saidnnput circuit Vto`ifaselisiih"circuitto present a high capacitiveimpedance at the output frequency, whereby the phase relations are such that output frequency energy is fed back` regeneratively from said output circuit to said input circuit.

13. A frequency multiplying circuit arrangement comprising an electron discharge device having at least three electrodes determining input and output terminals, a cavity resonator input circuit coupled to the input terinl'swtmppl'yw wave of given frequency to said electron discharge device, said input circuit being constructed and arranged to be parallel resonant at said given frequency, an additional impedance coupled to said input circuit to cause such circuit to present a high impedance at a frequency gubstantiallygrcaterwthanwthc frequency of said given frequencypyvayehand a cavity resonator output circuit coupled to the output terminals to derive an out# put wave having a frequency which is a multiple of said iven frequency. 14. A frequency multiplying circuit arrangement comising an electron discharge device having at least three electrodes determining input and output` terminals, one of said electrodes being a substantially planar control electrode,y an inputmcircuit coupledito the nput't'e'r'minals to apply a wave of givenfequency to said electron discharge device, said input circuit comprising a cavity resonator having a wall portion lying in the plane of said control electrode and said input circuit being constructed and arranged to be parallel resonant at said given frequency; Van additional impedance coupled to said input circuit to cause such circuit to present a high impedance at a frequency substantiallygreater than the frequency of said given frequency wave, and an output circuit coupled to the output terminals to derive an output wave having a frequency which is a multiple of said given frequency, said output circuit comprising a separate cavity resonator having a wall portion in common with said first-mentioned wall portion.

15. A frequency multiplying circuit arrangement comprising an electron discharge device having at least three electrodes determining input and output terminals, 'an input circuit coupled to the input terminals to apply a wave of given frequency to said electron discharge device, said input circuit being constructed and arranged t`be parallel resonant at said given frequency, an additional impedance coupled to said input circuit to cause such circuit to present a high impedance at a frequency substantially greater than the frequency of said given frequency wave, and an output circuit coupled to the output terminals to derive an output wave having a frequency which is a multiple of said given frequency, said additional impedance causing said inputl circuit to be parallel resonant at a frequency lying between four and twelve percent below the frequency of said output wave.

References Cited in the tile of this patent UNITED STATES PATENTS 2,407,074 Green Sept. 3, 1946 2,455,824 Tellier et al. Dec. 7, 1948 2,577,454 Diemer Dec. 4, 1951 

